1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device including an insulating substrate.
2. Description of the Background Art
A manufacturing process of a semiconductor device including semiconductor elements disposed on a circuit pattern formed on an insulating substrate includes a step of bonding the insulating substrate to a heat dissipation plate. When the insulating substrate (member that is a ceramic plate including metal patterns bonded onto both sides thereof) is bonded to, for example, the heat dissipation plate with solder, thermal stress upon the solder bonding generates tensile stress in the insulating substrate, resulting in a crack in the insulating substrate. The thermal stress is generated and concentrated in pattern end portions in four corners of the insulating substrate.
As an example of conventional measures against the thermal stress, Japanese Patent Application Laid-Open No. 2005-11862 discloses a technology of forming a front pattern and a rear pattern of the metal pattern into a set pattern.
The technology in Japanese Patent Application Laid-Open No. 2005-11862 can reduce the thermal stress generated in the insulating substrate. However, to improve yields of the product, the thermal stress needs to be further reduced.